The invention relates to a method for the determination of a characteristic curve of a hybrid separating clutch of a hybrid vehicle without a test stand, with the hybrid separating clutch connecting or disconnecting an internal combustion engine and an electric motor, and the hybrid separating clutch, starting from a position at which it assumes an unactuated state, being slowly actuated and the clutch characteristic curve being determined as a function of the clutch torque over a path of the clutch separating clutch.
DE 10 2010 024 941 A1 discloses a method for controlling a duplex clutch transmission with at least two partial drivetrains, allowing each of them to be coupled via a clutch to an internal combustion engine. During drive operation of the vehicle comprising the duplex clutch transmission a bite point of the clutch is determined independent from the engine torque. This bite point is an essential support point for a clutch characteristic curve, which states the clutch torque transmitted at a predetermined path traveled by the clutch. This bite point is determined during the startup routine of the vehicle and is then adapted during operation of the vehicle in order to adjust the clutch characteristic curve.
In a hybrid vehicle with a hybrid drivetrain the drive resistance can be overcome by two independent energy sources, such as fuel of an internal combustion engine and electric energy from a traction battery of an electric motor by converting them into mechanic energy. A method is known from DE 10 2008 030 473 A1 for the determination of the bite point of an automatic hybrid separating clutch. The bite point of the hybrid separating clutch arranged between an internal combustion engine and an electric traction drive is determined when the internal combustion engine is stationary by slowly closing the hybrid separating clutch and evaluating the influence of the slowly closing hybrid separating clutch upon the electric machine of the electric traction drive rotating with a predetermined speed.
The clutch characteristic curve of the hybrid separating clutch must be determined for proper operation. For this purpose the clutch is closed until reaching a torque specific for the respective application and the characteristic curve of the clutch torque is determined over the path. This is usually performed on a test stand. In particular in mechanic shops, due to the lack of such a test stand, the clutch characteristic curve cannot be learned for newly installed hybrid separating clutches.